1. Field of the Invention
The present invention is related to a backlight module and related manufacturing method and operation interface, and more particularly, to a backlight module and related manufacturing method and operation interface capable of emitting lights for a period of time when power supply is shut down.
2. Description of the Prior Art
With technology advancement, portable electronic devices, such as cellular phones, personal digital assistants, MP3 players, hand-held videogame devices, etc., are widely used in daily life. In order to allow a operation to keep handy, a portable electronic device is equipped with a rechargeable battery, to store operating power. Due to limited electricity stored by the rechargeable battery, how to decrease power consumption of the portable electronic device during operation becomes a goal in the industry.
In the portable electronic device, except an operating circuit and an output interface (e.g. monitor, speakers, etc.), an operation interface (e.g. keypads or keyboard) is one of power consuming elements. In general, for convenience or fascinating appearance, the operation interface of the portable electronic device comprises a backlight source to show corresponding characters clearly. To reach such effect, the prior art utilizes a light guide film to uniformly emit light generated by a light emitting unit. Please refer to FIG. 1. FIG. 1 is a cross-sectional view diagram of a backlight module for a keypad or keyboard in the prior art. In FIG. 1, according to a principle of light reflection, a light guide film 100 uniformly transmits light (represented by dotted lines in FIG. 1) generated by a light emitting unit 102 (e.g. light-emitting diode) to all areas of the keyboard. An oblique area A is corresponding to a keypad. Therefore, in order to obviously show a character corresponding to the keypad, the prior art drills a hole or prints special paint on the oblique area A, to emit light transmitted inside the light guide film 100 from the oblique area A.
Since the light guide film 100 can uniformly transmit light generated by the light emitting unit 102 to all the areas, the portable electronic device only requires a few light emitting units, to provide backlight to all keypads or the keyboard. Meanwhile, via the principle of light reflection, a forming position of the light emitting unit 102 is not limited, which benefits mechanism arrangement. However, the light guide film 100 can only transmit light; that is, once the light emitting unit 102 works, the oblique area A luminesces. Under such circumstances, when the user uses the portable electronic device, the light emitting unit 102 has to function continuously to show characters on keypads. Hence, power consumption is increased.
Therefore, how to form a backlight module which can store light energy to decrease power consumption of the operation interface in the portable electronic device becomes a goal in the industry.